/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package volcengineutil

// Copy from https://github.com/aws/aws-sdk-go
// May have been modified by Beijing Volcanoengine Technology Ltd.

import (
	"reflect"
	"regexp"
	"strconv"
	"strings"

	"github.com/jmespath/go-jmespath"
)

var indexRe = regexp.MustCompile(`(.+)\[(-?\d+)?\]$`)

// rValuesAtPath returns a slice of values found in value v. The values
// in v are explored recursively so all nested values are collected.
func rValuesAtPath(v interface{}, path string, createPath, caseSensitive, nilTerm bool) []reflect.Value {
	pathparts := strings.Split(path, "||")
	if len(pathparts) > 1 {
		for _, pathpart := range pathparts {
			vals := rValuesAtPath(v, pathpart, createPath, caseSensitive, nilTerm)
			if len(vals) > 0 {
				return vals
			}
		}
		return nil
	}

	values := []reflect.Value{reflect.Indirect(reflect.ValueOf(v))}
	components := strings.Split(path, ".")
	for len(values) > 0 && len(components) > 0 {
		var index *int64
		var indexStar bool
		c := strings.TrimSpace(components[0])
		if c == "" { // no actual component, illegal syntax
			return nil
		} else if caseSensitive && c != "*" && strings.ToLower(c[0:1]) == c[0:1] {
			// TODO normalize case for user
			return nil // don't support unexported fields
		}

		// parse this component
		if m := indexRe.FindStringSubmatch(c); m != nil {
			c = m[1]
			if m[2] == "" {
				index = nil
				indexStar = true
			} else {
				i, _ := strconv.ParseInt(m[2], 10, 32)
				index = &i
				indexStar = false
			}
		}

		nextvals := []reflect.Value{}
		for _, value := range values {
			// pull component name out of struct member
			if value.Kind() != reflect.Struct {
				continue
			}

			if c == "*" { // pull all members
				for i := 0; i < value.NumField(); i++ {
					if f := reflect.Indirect(value.Field(i)); f.IsValid() {
						nextvals = append(nextvals, f)
					}
				}
				continue
			}

			value = value.FieldByNameFunc(func(name string) bool {
				if c == name {
					return true
				} else if !caseSensitive && strings.ToLower(name) == strings.ToLower(c) {
					return true
				}
				return false
			})

			if nilTerm && value.Kind() == reflect.Ptr && len(components[1:]) == 0 {
				if !value.IsNil() {
					value.Set(reflect.Zero(value.Type()))
				}
				return []reflect.Value{value}
			}

			if createPath && value.Kind() == reflect.Ptr && value.IsNil() {
				// TODO if the value is the terminus it should not be created
				// if the value to be set to its position is nil.
				value.Set(reflect.New(value.Type().Elem()))
				value = value.Elem()
			} else {
				value = reflect.Indirect(value)
			}

			if value.Kind() == reflect.Slice || value.Kind() == reflect.Map {
				if !createPath && value.IsNil() {
					value = reflect.ValueOf(nil)
				}
			}

			if value.IsValid() {
				nextvals = append(nextvals, value)
			}
		}
		values = nextvals

		if indexStar || index != nil {
			nextvals = []reflect.Value{}
			for _, valItem := range values {
				value := reflect.Indirect(valItem)
				if value.Kind() != reflect.Slice {
					continue
				}

				if indexStar { // grab all indices
					for i := 0; i < value.Len(); i++ {
						idx := reflect.Indirect(value.Index(i))
						if idx.IsValid() {
							nextvals = append(nextvals, idx)
						}
					}
					continue
				}

				// pull out index
				i := int(*index)
				if i >= value.Len() { // check out of bounds
					if createPath {
						// TODO resize slice
					} else {
						continue
					}
				} else if i < 0 { // support negative indexing
					i = value.Len() + i
				}
				value = reflect.Indirect(value.Index(i))

				if value.Kind() == reflect.Slice || value.Kind() == reflect.Map {
					if !createPath && value.IsNil() {
						value = reflect.ValueOf(nil)
					}
				}

				if value.IsValid() {
					nextvals = append(nextvals, value)
				}
			}
			values = nextvals
		}

		components = components[1:]
	}
	return values
}

// ValuesAtPath returns a list of values at the case insensitive lexical
// path inside of a structure.
func ValuesAtPath(i interface{}, path string) ([]interface{}, error) {
	result, err := jmespath.Search(path, i)
	if err != nil {
		return nil, err
	}

	v := reflect.ValueOf(result)
	if !v.IsValid() || (v.Kind() == reflect.Ptr && v.IsNil()) {
		return nil, nil
	}
	if s, ok := result.([]interface{}); ok {
		return s, err
	}
	if v.Kind() == reflect.Map && v.Len() == 0 {
		return nil, nil
	}
	if v.Kind() == reflect.Slice {
		out := make([]interface{}, v.Len())
		for i := 0; i < v.Len(); i++ {
			out[i] = v.Index(i).Interface()
		}
		return out, nil
	}

	return []interface{}{result}, nil
}

// SetValueAtPath sets a value at the case insensitive lexical path inside
// of a structure.
func SetValueAtPath(i interface{}, path string, v interface{}) {
	rvals := rValuesAtPath(i, path, true, false, v == nil)
	for _, rval := range rvals {
		if rval.Kind() == reflect.Ptr && rval.IsNil() {
			continue
		}
		setValue(rval, v)
	}
}

func setValue(dstVal reflect.Value, src interface{}) {
	if dstVal.Kind() == reflect.Ptr {
		dstVal = reflect.Indirect(dstVal)
	}
	srcVal := reflect.ValueOf(src)

	if !srcVal.IsValid() { // src is literal nil
		if dstVal.CanAddr() {
			// Convert to pointer so that pointer's value can be nil'ed
			//                     dstVal = dstVal.Addr()
		}
		dstVal.Set(reflect.Zero(dstVal.Type()))

	} else if srcVal.Kind() == reflect.Ptr {
		if srcVal.IsNil() {
			srcVal = reflect.Zero(dstVal.Type())
		} else {
			srcVal = reflect.ValueOf(src).Elem()
		}
		dstVal.Set(srcVal)
	} else {
		dstVal.Set(srcVal)
	}

}
